The issue revolved around a poster at the Cheltenham Festival in March this year, which claimed that Betfair’s odds are “40 percent better than SP [Starting Price]” which Straight Statistics challenged as a breach of the advertising code.

Straight Statistics argued that the natural interpretation most punters would put on Betfair's claim was that if you placed a bet with Betfair, you stood to gain a 40 percent better return than betting at SP. The organisation complained that this was misleading, because long-priced horses are much longer-priced on Betfair, and therefore distort returns calculated in this way.

The average punter backs a short-priced winner much more often than a long-priced winner. “It follows that this method of comparison misleads punters, greatly exaggerating the Betfair advantage” the SS complaint alleged.

The Straight Statistics statement claims that Betfair itself admits that its claim would only be true if the punter put a bet on every winner over a given period and compared his returns to those from betting at SP.

In adjudicating the matter, the ASA found that the claim “40 percent better than SP” was not qualified in any way and that consumers were therefore likely to infer that such a figure was typical of what they could expect. The figure used by Betfair was skewed and had not been shown to be typically representative of the difference between the Betfair SP and the SP. The claim was consequently likely to mislead, and the ASA ruled that the claim must not again appear.

"We are delighted that our complaint has been upheld," a statement on the Straight Statistics website said this week. "We are strongly in favour of the punter getting a good deal, but misrepresentation must be stamped on hard."